With the widespread use of computer mapping tools and mapping applications, consumer demand for ready access to map data continues to grow at a high rate. While consumers have come to desire fast access to map data, the sheer amount of map data required to run these mapping applications places a premium on data management, both at a device level and at a network level. This premium may limit the effectiveness of mapping applications, which typically require comparatively large amounts of network data.
Mapping applications are found in a variety of mobile devices, including car navigation systems, hand-held GPS units, mobile phones, and portable computers. These applications are among the most frequently used applications and are considered, by some, necessary for personal safety. Although the underlying digital maps are easy to use from a user's perspective, creating a digital map is a data intensive process. Every digital map begins with a set of raw data corresponding to millions of streets and intersections. That raw map data is derived from a variety of sources, each providing different amounts and types of information. To effectively map a location, locate a driving route between a source and a destination, identify points of interest, etc. requires substantial amounts of data. Furthermore, many mapping applications require a display of different map data at different zoom levels, i.e., different scales, where the amount of detail and the nature of that detail changes at each zoom level. For example, at a lowest zoom level, scaled furthest away from a target, the map data may contain the boundaries of continents, oceans, and major landmasses. At subsequent zoom levels, that map data may identify countries, states, homelands, protectorates, other major geographic regions. While at even further subsequent zoom levels, that map data may contain major roads, cities, towns, until eventually the map data contains minor roads, buildings, down to even sidewalks and walk ways depending on the region. The amount of detail is determined by the sources of information used to construct the map data at each zoom level. But no matter the zoom level, the amount of information is voluminous and generally too large for storage, in total, on mobile devices and too large for continuous download over a wireless communication network.
In operation, mapping applications typically download map data to the mobile device through a wireless communication network and in response to a user entering a location of interest and/or based on the current location of the mobile device, such as the current global positioning satellite (GPS) data or current cellular network location data for the device. A conventional technique for downloading map data is to have the mobile device communicate this location data to a remote processor on the wireless communication network, which, in response, downloads all map data to the mobile device or the map data requested for display to the user.
Map data may generally be stored in blocks known as map data tiles, where the number of map data tiles increases with zoom level. The remote processor provides a subset of the available map data tiles for a particular location or region to the mobile device for storage and display at any particular time via a map display application. By providing large numbers of map data tiles, the mobile device may buffer the map data for display to the consumer as the consumer scrolls across an area using the mapping application looking for adjacent or other mapping locations. However, the larger the number of map data tiles provided at any particular time increases the download time and buffer memory usage while the user is using the map display application.
Map data tiles may be downloaded and cached in an inefficient manner that may not take advantage of differences in a threshold level of map data necessary to render different portions of a map surface at different viewing angles. This may be especially true when rendering a three-dimensional map having a viewing window that is tilted at an angle that exposes various viewing depths of the map surface. As a result, there is a need to have more intelligent mechanisms for retrieving (e.g., downloading) and/or rendering map data, in particular map data tiles, to sufficiently satisfy visual requirements of a three-dimensional map without wasting bandwidth and processing services.